1. Technical Field
The present invention relates to a MEMS device used to eject liquid or the like and a liquid ejecting head, and in particular, relates to a MEMS device provided with plural movable regions and electrodes corresponding to the movable regions, and a liquid ejecting head.
2. Related Art
Microelectromechanical systems (MEMS) devices including plural movable regions have applications in a variety of apparatuses (for example, liquid ejecting apparatus, sensors, and the like). For example, a liquid ejecting head, this being one type of MEMS device, is provided with pressure chambers that have a portion bounded by the movable regions described above, piezoelectric elements that displace the movable regions, nozzles that are in communication with the pressure chambers, and the like. An image recording apparatus such as an ink jet printer or an ink jet plotter is an example of a liquid ejecting apparatus mounted with such a liquid ejecting head. Recently, liquid ejecting heads have found applications in various types of manufacturing apparatuses that utilize the ability to accurately land minute amounts of liquid at specific positions. For example, liquid ejecting heads have applications in display manufacturing apparatuses that manufacture color filters for liquid crystal displays or the like, electrode forming apparatuses that form electrodes for organic electroluminescent (EL) displays, field emission displays (FEDs), and the like, and chip manufacturing apparatuses that manufacture biochips (biochemical elements). In the recording heads of image recording apparatuses, liquid ink is ejected. In colorant ejecting heads for display manufacturing apparatuses, solutions of R (red), G (green), and B (blue) colors are each ejected as respective types of liquid. In electrode material ejecting heads for electrode forming apparatuses, a liquid electrode material is ejected as one type of liquid, and in bioorganic matter ejecting heads for chip manufacturing apparatuses, a bioorganic matter solution is ejected as one type of liquid.
In the liquid ejecting heads described above, the piezoelectric elements are driven by voltages (electrical signals) applied to the piezoelectric elements, and configuration is such that pressure fluctuations in the liquid inside the pressure chambers arise so as to eject liquid from the nozzles. Here, wiring that is used to apply voltages to the piezoelectric elements is laid out from the piezoelectric elements toward the outside of the movable regions, and the wiring is connected to a wiring substrate through electrodes. Such electrodes provided in a row along the array direction of the piezoelectric elements (namely, the pressure chambers) with a pitch that is the same as the array pitch of the piezoelectric elements. As described in JP-A-2009-056662, a configuration is adopted in which the electrodes are arrayed above the pressure chambers in the same arrangement as the arrangement of the pressure chambers.
Accompanying an increase in nozzle density, there is a trend to reduce the array pitch of electrodes similarly to the array pitch of the piezoelectric elements. Namely, there is a trend to move electrodes corresponding to adjacent piezoelectric elements closer together. As electrodes move closer together, there is a tendency for shorting to occur between electrodes resulting from electrical discharge, migration, or the like between the electrodes. When such faults occur between electrodes, liquid is not ejected from the nozzles as expected, and the reliability of the liquid ejecting head is decreased.